Puerto Rico operated as a tax haven under U.S. Internal Revenue Code (IRC) Section 936. Firms in the pharmaceutical industry accounted for approximately 50% of tax credits awarded and 20% of employment under the program. The U.S. Congress eliminated the tax exemption program in 2006, creating a...

In this paper we propose Granger (non-)causality tests based on a VAR model allowing for time-varying coefficients. The functional form of the time-varying coefficients is a Logistic Smooth Transition Autoregressive (LSTAR) model using time as the transition variable. The model allows for...